I recently updated my project to use SFML 1.6 (Mac OS X).
I'm using direct OpenGL to render a 3D tile-based map (aka 2.5D), with either a perspective or orthographic projection.
However, I've found that once I use either glOrtho or gluPerspective, I can't switch to the other later (after I call app.Display). If I call glOrtho first, it gets stuck in orthographic; if I call gluPerspective, it's stuck in perspective.
It's most likely a fault in my code somewhere; however, it worked perfectly in 1.5, so I suspect it's something to do with SFML. If needed, I could try creating a minimal example.